Add 'role' data attribute. Note, that 'role' attribute is a part of reach ARIA API described here: http://www.w3.org/TR/wai-aria/ Among 'role', it defines lots of aria-* attributes

fun main () : transaction page =
    let
        return <xml>Hi {[alice]} and {[bob]}!</xml>
    where
        val alice = "Alice"
        val bob = "Bob"
    end